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Planetary gear train (PGT) is widely used in a variety of fields such as helicopters and aircraft engines. The failure of meshing gear often happens in the PGT due to the working condition of high speed, variable load, high-frequency excitation, assembly error etc. However, the causes of gear failure are still insufficiency, especially in the condition of high speed and high-frequency excitation. In this work, the engaging force between gear meshing pair of the PGT under high-frequency excitation is studied using the proposed position-correlated modal properties calculation method, which is established by incorporating the effect of meshing position and meshing phase difference of each contact pair into the free vibration model to study the modal properties of the PGT at different meshing positions. The corresponding engaging force responses based on the position-correlated modal properties are investigated. The simulation results show that the higher-order natural frequencies of the system are greatly affected by the meshing position. The peaks of engaging force occur at meshing positions where the natural frequencies are equal to the excitation frequency, which can be the potential cause of the gear damage.

A high speed on/off valve Actuator (HSVA) is a main interface between electronic control and hydraulic system for most fluid power applications such as braking systems of vehicles and aircrafts. Accurate theoretical model is the key to control the high speed on/off valve smoothly. However, modeling of a HSVA is a challenging difficulty due to the unavoidable multi-physics coupling problems in practice. For establishing mathematical model of a HSVA accurately, this study dismantles the coupling model into three interrelated sub-models, including a mechanical sub-model, an electromagnetic sub-model, and a thermal sub-model. And then, these three subsystems are modeled as a spring/mass/damper system, a nonlinear resistor/inductor system and a multi-wall heat transfer system, separately. At last, the feasibility of above three sub-models is verified by comparing the simulation results with the experimental results obtained on a test bench. Our study shows that the three subsystems are coupled to each other through resistance, displacement, and temperature. Besides, our results can be regarded as a research tool for future investigation and development of the Solenoid valves.

Knowing vehicle sideslip angle is important and useful in various vehicle active safety applications. However, equipment which could directly measure sideslip angle is usually too expensive for industrial applications, so a reliable, affordable sideslip angle observer is necessary. Model-based observer is affected by the model uncertainty, non-linearity and the road friction inaccuracy. Sensor-based observer might be easily affected by the sensor noise and the bias induced by the road micro-uneven. Thus, an unscented Kalman filter (UKF)-based adaptive variable structural observer with dynamic correction (AUKF) for vehicle body sideslip angle is brought forward in this study. First, an UKF observer with adaptive parameters is used to compensate the model uncertainty. Then, a sensor-based observer is applied to realise a variable structure observer to compensate the estimation error in the highly non-linear region. A pseudointegral method and a zero point reset method are adopted to dynamically correct the bias drift problem in the integral. Both simulations and real vehicle tests validated the proposed approach. The accurate vehicle sideslip angle is measured by a differential global positioning system. Results show that the proposed approach has better performance compared with traditional UKF method, and makes a good foundation for stability control.